Hi i posted on here a while ago about this same problem, when im operating the back digging arm on my backhoe the joystick controls go stiff as if there is some kind of backpressure in the system i have also found that if i use the front bucket or any other hydraulic function on the machine when using the back arm the levers go stiff, i have checked return lines,changed hydraulic oil and filter, removed various valves for inspection but cant find anything wrong,im wondering if there is an internal crack in one of the valve blocks, has anyone ever had this before with this machine? cheers kev
Hi kjiplant, you've been having this problem for some time now. I really can't help you much as I don't know your machine. I remember you were describing you have pilot operated controls for the backhoe. Does the front loader valve operate by pilot controls as well? Or is the loader valve direct linkage/lever control? Does the stiffness of lever and/or pressure trying to return hoe lever to center affect all four hoe functions or just one hoe function?
Don't know your machine, however some valve banks have a bleed off orfice at the base end of the spool to prevent oil leaking past the spool into the area behind the spool and creating a hydraulic lock. Each spool would have one leading to a drilled passage in the valve, through a check valve to the return to tank port. If that check valve were to stick or a piece of trash plugged the drilled passage this could allow pressure to build up behind the spool.
Hi thanks for the replys.All of the functions are affected for the rear controls but the front bucket controls are fine. If i hold the front bucket control so the relief valve blows then the rear levers go stiff, it seems to be if the hydraulics are under any pressure then the rear joysticks get back pressure some how.When im just operating the controls with the bucket in the air its all fine but when i put the bucket in the ground and make the machine work thats when i get the problem.:beatsme
Let me be clear, when you aren't using the loader the back hoe valve works OK? If you are using the loader to dig or load, the backhoe valve levers get tight? 1. Do both valves use the same pump? 2. If so, which valve has priority (first in line from the pump)? 3. Are both valves pilot operated? 4. When would you be using the front loader and the backhoe at the same time?
HI sorry, the backhoe levers go tight without using the front loader i just meant that i noticed that when i operate the front loader that this makes the levers tight also.Both valves have the same pump and both are teed into the same return line which makes me think that it must be pressure getting back into the valve from the return side but i cant see any check valves on the valve block.both valves are pilot operated also. The backhoe valve is supplied with oil from the loader valve as far as i can make out.
Hi sorry the front loader is also pilot operated from what i can see.
Ok, got it. The reason I asked was I was thinking you may have had a faulty pressure regulator for the pilot circuit, but if the front loader is a pilot controlled system as well, and works proper, I tend to think the problem is not pilot pressure regulator. It's really difficult to troubleshoot this without a schematic of the system and I haven't found any info on your machine here in the US. Could you post some pics of the pilot valves? Have you actually checked the pilot pressure going to backhoe pilot valves to make sure it's operating at proper pressure? And have you checked that the return to tank ports of the pilot control valves are in fact venting oil back to tank?